1. From the Department of Public Health (A.E.K.), Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands; the Department of Public Health (M.A.), Erasmus Medical Center, Rotterdam, the Netherlands; the Department of Epidemiology and Biostatistics (M.A.), School of Health, Shahrekord University of Medical Sciences, Shahrekord, Iran; and the Population Research Centre (F.J.), Faculty of Spatial Sciences, University of Groningen, Groningen, the Netherlands.